Apparatus for drying gelatin capsules



5 Sheets-Sheet 1 i BY a'v, 71W VWM ATTUHNEYS.

March 17, 1959 R. P. scHERl-:R

APPARATUS FOR DRYING GELATIN CAPSULES Original Filed April 18. 1955 5Sheets-Sheet 2 N VEN TOR.` wdm Q/Wa/M.

TTRVEYAS.

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March 17, 1959 R. P. scHERr-:R

APPARATUS FOR DRYING GELATIN CAPSULES original Filed April 18, 1955 5Sheets-Sheet 3 INVENTOR. wfdcwm "5w, aww

ATTRNFY.

March 17,1959 R.v P. SCHEREB. 2,877,562.

APPARATUS FOR DRYING GELATIN CAPSULES Original Filed April 18, 1955 5Sheets-Sheet 4 I INVENToR:

ATTRNEYS.

March v17, 1959 R. P. scm-:RER

APPARATUS FOR DRYING GELATIN CAPSULES Robert Pauli Scherer, GrossePointe, Mich., assignor to R. P. Scherer Corporation, Detroit, Mich., acorporation of Michigan Original application April 18, 1955, Serial No.501,971. Divided and this application November 29, 1957, Serial No.702,495

Claims. (Cl. 34-57) rof a freshly-prepared capsule will contain asubstantial quantity of water, say 35 to 40% `Freshly-prepared capsulesare very weak mechanically and ditllcult to handle for packaging,shipping or storing until their strength has been increased byevaporating some of the water from the gelatin shell composition. Beforeevaporation of the moisture, the capsule exhibit plastic and adhesivecharacteristics, tending to cause them to deform and to mass together ingroups of bunches. Furthermore, excess water in the shell may acceleratereaction with the capsule content. nIt is important, therefore, that thecapsules be dehydrated immediately after preparation. Drying is commonlyperformed by immersing the capsule in acetone to extract the water, butthe extraction must be carried out after the capsules have cooled forabout one-half hour. Otherwise, the surface of the shell becomes checkedand dulled due to the differential rate of water extraction between theouter and inner surfaces of the shell. During this cooling perioddeformation and massing is ditlicult to avoid. Dehydration has also beencarried out completely in a tunnel drier. Since the temperature of thedrying air in a tunnel drier must be maintained at below 82 F. toprevent softening and deformation of the gelatin shell, the drying timeis far too long to be economical.

IOne object of the present invention is to provide an apparatus forquickly drying the gelatin shell of capsules in which the contents ofthe capsules are heated by radiant energy While the surface of the shellis being air-cooledl to maintain the temperature thereof below thesoftening point of the gelatin.

Another object is to provide an apparatus `for drying a large batch offreshly-prepared capsules without massing or distortion bysimultaneously and continuously agitating the mass to keep the capsulesseparated, exposing the capsules to infra-red light rays and passing airthrough the capsules to cool the gelatin shell.

Another object is to provide an apparatus which is peculiarly adaptedfor continuously drying gelatin capsules, in accordance with the processof the present invention.

Another object is to provide an apparatus in which the soft, tackycapsules may be constantly agitated to prevent massing together, saidapparatus comprising a foraminous supporting surface which keeps thecapsules in motion, infra-red lamps for heating, and means forcirculating cooling air past the moving capsules.

United States Patent O ICC a series of rotating drums for agitating thecapsules, and which utilizes a stream of air for conveying the capsulesfrom one drum to the next.

IOther and further features and objects of this invention will becomeapparent from the following description as illustrated by theaccompanying drawings, in which:

Figure 1 is a front elevational view of the apparatus employed forcarrying out the invention;

Figure 2 is an end elevation of the lapparatusas viewed from the rightend of Figure 1;

Figure 3 is an end elevation of the apparatus as viewed from the leftend of Figure 1;

Figure4 is a fragmentary sectional view taken along the line 4--4 ofFigure 3 showing particularly the construction and mounting of onetumbling drum;

Figure 5 is a perspective view of the arcuate door as semblymounted'between the drum compartments; and

Figure 6 is a perspective View of the ductwork of the apparatus showingthe direction of air flow therethrough.

VBriefly, the apparatus comprises a series or line of tumbling drums 10rotatably mounted, with their axes in alignment, on rollers 34 fixed tospaced, parallel driven shafts 14 and 16 extending lengthwise of themachine, as best shown in Figure 6. The circumferential face 10a of eachof the drums is made of a porous material so that air will pass freelytherethrough. The ends 10b of the drums are open. Each drum 10 isenclosed in a separate compartment 18 (see Figure 1) communicating withits neighbor through an arcuate door 20 which is xed to a rotatableshaft 21. Conditioned air is forced into each compartment through a duct30 joinin-g the compartment through the rear panel behind the drum.Infra-red lamps 6i) mounted below each drum, except the .iinal coolingdrum in compartment 18a, supply the heat required for ydrying thecapsules. Capsules to be dried are fed into the iirst drum, that is, thedrum at the right-hand end of the apparatus, as sho-wn in Figure l.After a predetermined drying period the capsules are transferred intothe adjacent drum on the left merely by opening the door 20. Thecapsules are being constantly tumbled in a rotary path as the drumrotates and as they are lifted to a point opposite the air inlet duct 30they become entrained in the stream of air ilowing into the drum. Theair stream is directed toward the door 20 because -of the angle at whichthe duct 30 joins the drum compartment, and when the door is open,carries the capsules through to the next drum. This transfer is repeatedintermittently, advancing the capsules from one drum to the next inpredetermined sequence, until the dried capsules nally Another object isto provide an apparatus comprising are discharged from the last drum inthe compartment 18a. Here the capsules are cooled before being subjectedto further handling.

Referring now to the structural details, the supporting shafts for thedrums 10 and the panels which define the compartments 18 are mounted onsuitable frame, indicated generally by the numeral 11. In the apparatusillustrated, six compartments are employed, but it will be understoodthat any convenient number may be used. As best shown in Figure 3, eachcompartment is enclosed by a rear panel 22, front panel 23, bottom panel24, and a curved, imperforate cover 2S, which swings from hinges 25a andjoins the panels 22 and 23 to completely enclose the top portion of thedrum 10. The compartment 18a at the left end of the machine has aperforated cover 26 which permits air to flow from the room into saidcompartment so that the capsules are cooled before discharge from theapparatus, as explained hereinbelow. In other respects the covers 25 and26 are identical. Preferably, the panels 22, 23 and 24 each comprise onepiece which extends the entire length of the machine. Bulkheads orpanels 28 separate the compartments 18 laterally, and each contains anopening 28a (Figure 4) approximately asrasea semi-circular inshape, andaligned with the openings b in the ends of the drums 10. The openings28a are those through which the capsules pass in being transferred fromYone drum to the next. Each opening 28a is closed with a separator plateor transfer door 20 (see Figure 5) xed to a shaft 21 rotatably mountedin brackets 31 secured to the bulkhead 28. The shaft 21 is coupled atone end Yto a conventional rotary solenoid 3S connected to a source ofelectrical power through a timer (not shown). At periodic intervalsdetermined by the timer, the solenoid is activated and serves to rotatethe shaft 21 to open the door to the position shown in dot and dashlines in Figure 4. Preferably, the door, when open, should form 'anangle with the lbulkhead smaller than 90. By restricting the angle ofopening in this manner, capsules that might fall from the stream of airbefore they are carried into the next drum will slide down the door intothe next drum, in the direction of the arrows in Figure 4.

The construction of the drums is best shown in Figure 4. Each of thedrums is identical in construction and is mounted on fourplastic-covered rollers or Wheels 34,

ltwo iixed to the front shaft 14 and two fixed to the rear shaft 16. Thedrum has a foraminous circumferential face 16a made from screen wire orthe like and circular openings 10b in both ends. For lifting thecapsules, ribs 10d, equally spaced about the circumference, are securedto the inside diameter of the drum. The inside corners 10c are bevelled,as indicated in the drawing, to concentrate the capsules on theforaminous surface 10a so that they will be subject to direct radiationfrom the infra-red lamps 60 mounted below the drum. Suitablecircumferential angular supports 10e are secured externally to thebevelled corners 10c of the drum for running contact with the plastictreads of the rollers 34. Shafts 14 and 16 carry the rollers, and arerotatably mounted in bearings (not shown) fixed to the frame of themachine. Both shafts are driven by a motor 36 which drives the shaft 38through a belt and pulley arrangement 40, 42. A second belt 44 istrained over a pulley 50 fixed to the shaft 3S, and over pulleys 46 and48 fixed to shafts 16 and 14, respectively.

To supply heat for drying the capsules, several infrared lamps 60,connected to a source of power (not shown) are mounted on a base 52supported by the panel 24 within each compartment 18, as best shown inFigure 3. The lamps are arranged so that the rays impinge directly onthe foraminous face 10a of the drum. In the drawing, three lamps areshown in each compartment, but more or less may be used as determined bythe size of the compartments and the wattage of the lamps. The lamps areof the variety that emit light Waves having a wave length of from 9,000to 15,000 angstrom units. For maximum Veliiciency in drying it isimportant that the wave length be within this range.

A System of ducts and blowers for moving conditioned air through thecompartments is best shown in Figures 1 and 6. The main air inlet to thecompartments is through intake opening 71 of the blower 72 located atthe right end of the machine. The discharge side of the blower 72connects to a riser duct 30 which skirts the duct 62 and returns as ahorizontal portion 301) which connects to the back of the panel 22through an opening 30a. It will be noted from Figure l that the upperhorizontal portion 30b of the duct 30 joins the opening in the rearpanel 22 at an acute angle so that the air discharged from kthe duct isdirected toward the opening in the left or far end of the drum, asViewed in Figures 1 and 6. By directing the air stream in this manner,the air may be utilized not only for removing moisture from thecapsules, but also for Waiting the capsules from one drum to the .nextwhen vthe door 20 is open. Air introduced through the opening 'llailowsthrough the capsules which are being tumbled and heated simultaneouslywithin the .drum .10, Vout through the foraminous face 10a, through theopening 24a in the bottom panel "24 of the compartment adjacent theinfra-red lamps, and into the intake side of the next blower 72. Thedischarge side of the lower 72 connects to the next duct 30 forintroducing air, which has now been raised in temperature to some extentby passage through the lirst compartment, into the next compartment 18.Each compartment 18 has an identical blower 72 which sucks the airtherefrom and forces it into the compartment to the left. Thepenultimate blower in the line discharges moisture-'laden air into astack 74 which is a vertical extension of the duct 36. A damper 75(Figure 3), operated by rotary solenoid 76, is provided in the duct 30so that the air may be blocked off from the discharge duct 74 andpermitted to flow into the compartment 18a, through opening 30a, when itis desired to transfer the capsules in this last compartment from themachine. Normally, the damper 75 will be closed so that the air comingup through the duct 3h will be discharged into the exhaust duct 74. Thesolenoid 76 is in the same-circuit as the solenoid 35 operating the door20 of compartment 18a so that the air stream begins to convey thecapsules from the drum as soon as the door opens.

A duct 62, running lengthwise of the machine behind the compartments 18,serves to convey supplementary conditioned air drawn from the room, orother suitable source, to the central compartments 18. The quantity ofair introduced is suiicient to maintain constant'volume in each of thecompartments. Duct 62 connects to the discharge side of blower 66 at theleft end of the machine, which draws relatively cool air from the roomthrough the last or cooling compartment '18a via intake 66a whichconnects to openings 24a (Figure 3) in the panel 24. The cover 26enclosing compartment 18a is foraminous for this purpose. Theconditioned air is blown through duct 62 toward the opposite end of themachine. Dampers 67 are provided over openings 61 interconnecting theduct 62 with the compartments 18 through rear panel 22 to admit thedesired volume of air to the compartments.

The blowers 72 and 66 are driven from a common shaft 80, which connectsto a motor 84 as shown in Figure 3, by means of pulleys 81 and 82 xed tothe motor shaft and the shaft 80, respectively. V-belt 83 is trainedabout the pulleys 81 `and 82.

A hopper S6 is provided at the right end of the machine for chargingcapsules into the iirst drum, and suitable funneling means 87 is mountedon the left end of the machine to direct the capsules discharged fromthe last drum into containers for subsequent handling.

in operation, capsules to be dried are Ycharged into the hopper 86 atthe right end of the apparatus, as shown in Figure 1, from which theyare fed directly into the rst drum 10 in compartment 18. The motionimparted to the capsules must have both vertical and horizontalcomponents so that the capsules are moved in a circulatory path.Rotating drums have been found to be the preferable means for impartingthis motion. The oily lm which usually covers the exterior of thecapsule must be removed. The film results from application of oil to thegelatin ribbons from which the capsules are formed. The speed at whichthe drum rotates is important in preventing the capsules from massing oradhering together. For drums about sixteen inches in diameter, we havefound that 60 R. P. M. is a suitable speed. if the speed is increasedmuch beyond this point the capsules will be heldin contact with thecircumference of the drum by centrifugal force instead of being liftedby the ribs 10d to the peak of the circulatory path and then dropped. Ifmasses of capsules are permitted to remain in contact with each otherfor any prolonged period of time within the range of the infra-redlamps, fusion will result. If rthe speed is .reduced substantially belowl60 R. P. M., the capsules lack the momentum required to lift them tothe top of the circular path through which they are intended to ow, Itis essential that the capsules be lifted at least-to the level of airopening 30aso' that they`are subjected to the full flow ofpassingthrough the drum. The rotating drum has been found ltobe very effectivein keeping all the capsules constantly in Imotion, thus greatlyminimizing any tendency to fuse together. y

The first drum at the right end of the machine serves as a receiver forfreshly-prepared capsules. The capsules are charged'into the drum for apredetermined period of time, depending upon the size of the capsulesand the rate of manufacture. The door 20, activated by the solenoid 3S,is then opened to permit the capsulesto be transferred to the seconddrum. The air stream ows directly from opening 30a through the door ofthe compartment, catches thecapsules as they are lifted to the height ofthe air inlet, and wafts them into the next drum. After the machine hasvbeen in operation for some time and all the drums are lled, the4transfer at the end of the predetermined period to 30 minutes) beginswith discharge of partially dehydrated capsules from the cooling drum incompartment 18a. The door to the receiving means 87 is then closed, andthe door between the penultimate drum and the cooling drum is opened totransfer the capsules to the latter. In this way the capsules aresuccessively advanced. The capsules may befed intermittently, as well ascontinuously, into the rst drum from hopper86. When the capsules are being charged into the apparatus continuously, the cycle is suciently longso that even the fresh capsules transferred immediately after enteringthe rst drum are satisfactorily dried upon discharge at the opposite endof the machine.

An important feature of this apparatus is lthat by utilizing the airwhich is discharged from the adjacent compartment, the temperaturethereof progressively increases until maximum temperature (about 95 F.)is attained in the penultimate compartment 18, which is the compartmentadjacent cooling compartment 18a. The capsules are much better able tostand elevated temperatures after being partially dried and,consequently, the progressive elevation in air temperature results in arelatively rapid drying cycle without danger of adhesion. When a batchof capsules is finally discharged into the last drum 10 in compartment18a, they are cooled by air at 70 and a relative humidity of less than45% which is drawn from the room through the perforated cover 25enclosing the last compartment. The temperature lof the capsules shouldnot be greater than 85 F. after cooling. As indicated, the cooling airflows out of the'compartmentA 18a into the duct 66a and is forced by theblower 66 into the duct 62 for preheating. If the room is not airconditioned, air may be supplied at, proper temperature and relativehumidity through suitable conduits- (not shown) connecting to thelcompartment 18a. Air supplied to conduit 61 is normally drawn from theroom, but may be connected to the same source ifthe room air is notproperly conditioned.

It has been noted in operating the device described that irradiation byinfra-red rays will raise the temperature of `the contents of thecapsules to 135 to 145 F. The gelatin shell has a softening point ofabout 120 F. Consequently, it is necessary to flow air constantlythrough the mass of capsules to keep the gelatin surface of the shellcool and at the same time sweep out moisture that has been evaporated.It appears that the capsule walls themselves do not absorb the infra-redrays and are not heated directly by the rays, although the capsule wallswill receive heat from the contents of the capsulesv by conduction. Ihave found that if the wave length is greater than l5;00O`angstroms,the'ambient temperature surrounding the capsules. is excessively highand results in the formation of a skin on the surface of the capsuleswhich-'interferes with evaporation of the water'there- Cfrom; -If' thewave length is shorter than 9,000 angstroms, the energy is dissipatedthrough visible light which does envases ,not penetrate the shell. Thisalso causes the outside of the shell to dry r'st and case harden thecapsule.

' It is possible that the critical nature of the wave length range maybe due to selective absorption by the contents of the capsules. This isborne out by the fact that the capsule wall will soften even when thewave length is within the range specified if the oily iilm on thesurface has not been removed. Theoil appears toabsorb infraredradiation. It is important, therefore, that the capsules be pretreatedwith naphtha or acetone or other solvent which is capable of removingthe oily film from the surface.

As indicated, irradiation alone, or irradiation in conjunction withagitation, will destroy the capsules unless air is owing through themass. The air should be maintained at a temperature not in excess of 100F. and should preferably range from to 95 F. In the apparatus described,air entering the first drum is approximately 85 F. and after passingthrough the intervening compartments, enters the last drying drum atabout F. Temperatures as low as 70 F. may be used, but, of course, thiswill slow down the rate at which the moisture is evaporated. Therelative humidity of the air should not exceed 45% and preferably iswithin the range of 30-40%. Below 30% there is a tendency to case hardenthe shell. The rate of air flow through the drum should be such as todisplace continuously all the water vapor generated as the capsules aredried.

In the drying method of the invention, the capsule contents are heatedwhile the capsule walls are maintained in a relatively cool condition.Thus, the heat for water vaporization is conducted radially outwardlyfrom the capsule contents through the capsule Walls to dry them withoutformation of skin on the outside surface of the capsule wall. For thisreason the capsules are dried rapidly, etliciently and uniformly.Dehydration in this manner is continued until from 60-70%,

- preferably 63-68%, of' the original moisture content of thecap'suleshas been removed. This amount of moisture willbe removed in about twohours in accordance with the invention. The capsules may then be handledwithout fear of distortion and any further dehydration may beconveniently carried out in a tunnel drier. The final drying may beconducted in the present apparatus, but removal of-additional moistureis preferably done in a tunnel drier since agitation and air flow is nolonger critical. The finished capsules ordinarily contain about 12 to15% moisture. To reach this level about l2 to 16 hours is required inthe tunnel drier. V

A number of important advantages Vare obtained by drying capsules'inaccordance with the present invention:

(1) Capsules with thin walls maintain their molded original shape. Whenvdried on a supporting surfacein accordance with conventional practice,such capsules will squat or become at on the bottom.

(2) The welded seam joining the two capsule half shells, and formedduring manufacture, is much stronger by reason of heating the interiorsurface. This causes the abutting surfaces of the half shells to flowtogether to provide an integral bond.

(3) Because the drying time is greatly reduced, very little of theliquid contents within the gelatin shell, particularly water solublematerial, escapes to the atmosphere during drying.

(4) Continued agitation during drying tends to bring distorted capsulesback to their true shape.

What I claim as' new and desire to secure byLetters Patent of the UnitedStates is:

1. In an apparatus for drying soft gelatin capsules, a plurality ofaligned compartments including first, last and intermediate compartmentslaterally divided from each other by bulkheads, each containing a door,each compartment having an air inlet opening and an air outlet opening,said last compartment having a second air inlet opening, a rotatabledrum mounted in each compartment, saidl drum-having 1a foramincuscircumferential wall and --open` ends, 'the ends ,of'adjacent drumsfacing the door in the bulkhead therebetween, a vfirst blower having itsintake ,side communicating with a source of conditioned air and vits,discharge side communicating with the ,air inlet of vsaidfirstcompartment, a last blower having its intake Vside connected to theoutlet opening .of said last compartment, a blower associated with eachintermediate compartment havingits intake side connected to the lairoutlet of said intermediate compartment and its discharge side connectedto the air inlet of an adjacent compartment, means for directing vtheair stream entering each compartment through theair inlet-so as vto waftcapsules from the drum to the drum in an adjacent compartment throughthe open ends thereof upon opening said'door, and infra-red Ylampsmounted in said first and intermediate compartments Aadjacent the drumstherein for heating said capsules.

2. In an .apparatus 'for` drying soft gelatin capsules, a plurality of.aligned compartments including first, last and intermediatecompartments laterally divided from each other by bulkheads, eachcontaining a door, each compartmenthaving an air inlet opening and anair outlet opening, said last compartment having a perforated cover foradmitting air from the room, a rotatable drum mounted in eachcompartment, said drum having a foraminous circumferential wall and openends, the ends of adjacent drums facing the door in the bulkheadtherebetween, a first blower having its intake side communicating with asource of conditioned air and its discharge side communicating with theair inlet of said first compartment, a last blower having its intakeside connected to the outlet opening of said last compartment fordrawing air through said perforated cover to cool capsules in the drumin said compartment, a blower associated with each intermediatecompartment having its intake side connected to the air outlet of saidintermediate compartment and its discharge side connected to the airinlet of an adjacent compartment, means for directing the air streamentering each compartment through the air inlet so as to waft capsulesfrom the drum` to the drum in an adjacent compartment through the openends there of upon opening said door, and infra-red lamps mounted insaid first and intermediate compartments adjacent the drums therein forheating said capsules.

3. In an apparatus for .drying soft gelatin capsules, a plurality ofaligned compartments including first, last and intermediate compartmentslaterally divided from each other by bulkheads, each containing a door,each compartment having an air inlet opening and an air outlet opening,said last compartment having a. perforated cover for admitting air fromthe room, a rotatable drum mounted in eachcompartment, said drum havinga foraminous circumferential wall and open ends, the ends of adjacentdrums facing the door in the bulkhead therebetween, a i

first blower havingits intake side communicating with a sourceofconditioned air and its discharge side communicating with the air inletof said first compartment, a last blower having its intake sideconnected to the outlet opening of said last compartment for drawing airthrough said perforated cover tocool capsules in the drum in saidcompartment, the .discharge side of said last blower connecting to aduct having outlet ports to each intermediate compartment, a blowerassociated with each intermediate compartment having its intake sideconnected to the air outlet of said intermediate compartment and itsdischarge side connected to the airv inlet of an adjacent compartment,means for directing the air stream entering each compartment through theair inlet so as to waft capsules from the drum to a drum in an adjacentcompartment through the open ends thereof upon opening said dooryandinfra-red lamps mounted inv said first and in- *termediateV compartmentsadjacent' the drums therein for heating said capsules.

.4.k Iman apparatusfor dryingsoft gelatincapsules, a plurality ofaligned compartments including first, lastand intermediate compartmentslaterally divided from each other'by bulkheads, each containing a door,eachcompartment having an air inlet opening and an air outlet opening,said last compartment having a perforated cover for admitting air fromthe room, a rotatable drum mounted in each compartment, said drum havinga foraminous circumferential wall and open ends, the ends of adjacentdrums facing the door in the bulkhead therebetween, a iirst blowerhaving its intake side communicating with a source of conditioned airand its discharge side communicating with the air inlet of said firstcompartment, a last blower having its intake side connectedto the outletopening of said last compartment for drawing air through said perforatedcover to cool capsules in the drum in said compartment, the dischargeside of said last blower connecting to a duct having outlet ports toeach intermediate compartment, a blower associated with eachintermediate compartment having its intake side connected to the airoutlet of said intermediate compartment and its discharge side connectedto the air inlet of an adjacent compartment, means for directing the airstream entering each compartment through the air inlet so as` to waftcapsules from the drum to a drum in an adjacent compartment through theopen ends thereof upon opening said door, controlled means for openingsaid doors 4in timed relation to permit advancing said capsules from onedrum to the next, and infra-red lamps mountedin said first andintermediate compartments adjacent Ithe drums therein for heating saidcapsules.

5. ln an apparatus for drying soft gelatin capsules, a plurality ofaligned compartments including first, last, penultimate, andintermediate compartments laterally 'divided from -each other bybulkheads, each containing a door, each compartment having an air .inletopeningand an air outlet opening, said last compartment having aperforated cover for admitting air from the room, a rotatable drummounted in each compartment, said drum having a foraminouscircumferential wall and open ends, the ends of adjacent drums facingthe door in the bulkhead therebetween, a first blower having its intakeside communicating with a source of conditioned air and its dischargeside communicating with the air inlet of .said first compartment, a lastblower having its intake side connected to the outlet opening of saidlast compartment, a blower associated with each intermediate compartmenthaving its intake side connected to the air outlet of said intermediatecompartment and its discharge side connected to the air inlet of anadjacent compartment, a penultimate blower having its intake .sideconnected to the air outlet of said penultimate compartment and itsdischarge side connected to a forked duct, one branch of said forkedduct connecting to the air inlet of said last compartment, the otherbranch of said forked duct connecting to an exhaust duct, a damper insaid forked duct normally permitting air discharged from saidpenultimate compartment to flow into the exhaust duct,con trolledmeansfor closing said damper when lit is desired to cause said air toflow through the air inlet of said last compartment to remove capsulesfrom the drum therein, means for directing the air stream entering eachcompartment through the air inlet so as to waft capsules from the drumto the drum in an adjacent compartment through the open ends thereofupon opening said door, and infrared lamps mounted in said lirst,penultimate, andlintermediate compartments adjacent the drums thereinfor heating said capsules.

References Cited in the'le'ofthis patent 'UNITED STATES PATENTS1,102,662y Hobbs -..j July/'7,119.14 2,406,494 Ferris ..-Aug-.27,119.46

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